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Georeferencing via IfcSite and IfcProjectedCRS (IFC 4.3) #159
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It would be nice if you can share the IFC model to have a look. AFAIK the IFC Tunnel Project was addressing such issues more specifically, but I may be wrong here. Pinging @SergejMuhic. |
Hi, thanks for the response. I pasted the IFC4.3 example below. cheers
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Hello, there are two operations for maps available:
We have dealt with this problem in Tunnel, yes. We have prepared two (even three to be precise) concept templates for usages in the IFC spec. These draft templates provide the idea: |
Hi Below my new try. I tried to avoid the IfcMapConversion by directly placing the sites in GK coordinates. If there are errors in the code which cause wrong georeferencing or not proper construction of the models, please specify them as I'm new to this. @SergejMuhic Thanks for your response. I have identified IfcRigidOperation as possible option (4.10.6 Project Global Positioning Mapped) . I'd try it next if this approach does not work out. thanks
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We still get the model near Vienna, we have double checked the EPSG and this seems correct...can you double check? The first screen is for the first signal, the second one is for the position of the second signal. The file is better but still contains errors (IfcDirections, non existing IfcProperties,...) you can use the bSI Validation Service to have it checked... ...in the meantime, let's wait for the experts of this topic if they have something to say! |
Hi @michelangelo-acca, The question is: Why are the IfcSites properly georeferenced east of Vienna, but the IfcSignal relative displaced (0,0,0) to the site is in Rome?
Thanks :) |
@matgitbac can you wrap your IFC snippet as code?
Otherwise the # points to all existing issue in this repository. Thanks |
I wrapped it, but it messes up the layout. |
If you prefer, you can submit a pull request with your file (we have a Files folder). Then, just keep updating that file, or submit others. And then use the GitHub issue for discussion, just pointing at the file. This not only is the recommended workflow, but would also make the issue more readable for yourself and others. I can help if you need assistance |
nice on the eyes, wrapped version:
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Hi
Problem
In relation to my recent post in the General usability issues of docs #371 forum, I would like to understand how to properly georeference multiple small, distant (>5km distances, same Projected CRS) sites in one project.
I do not use IfcMapConversion, because a single set of transformation parameters would not be accurate enough for the large area.
Solution(s)
My present approach is that I define multiple sites and each site is defined by local placement (IFCAXIS2PLACEMENT3D, IFCCARTESIANPOINT and IFCDIRECTION).
In IfcCartesianPoint the coordinates are defined in the Gauß Krüger coordinate system and rotational angle to true north is defined in IfcDirection.
This way, the local 3D model coordinates need to be defined only once and can be reused in the sites.
However, as IfcProjectedCRS links only with IfcMapconversion, does it still make sense to include these to indicate that the site offsets are Gauß Krüger coordinates?
Is this the correct approach for georeferencing multiple distant sites in one project or is there a better “best practice” approach?
If there is a different approach to commonly apply, please provide some concrete examples with real data.
Thank you!
Cheers
Matthias
Require schema changes?
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noRequire documentation changes?
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noRule required
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